Modern computer systems require that a variety of hardware devices exist in specified states for stable operation. Often storage drives may exist in only one of several potential states at a time. For example, the potential states for physical or virtual storage drives may include: Up, Down, Reserved, or Suspended. The device states may be changed by operator console commands.
In a normal processing environment, it is possible for an incorrect change in device state to occur. For example, an operator could mistakenly change the state of a device to Up when the device is expected to remain in Reserved unless a disaster recovery event occurs. Such an incorrect state change can cause significant disruption in a software environment. With the advent of virtual tape drives, there may be hundreds of devices, each with its own expected state. Without automation, these virtual devices would be unmanageable, as operators regularly make mistakes and set important system devices to the wrong state.